function popup(url,w,h,sb)
{
	var centerx = (screen.width/2)-(w/2);
	var centery = (screen.height/2)-(h/2);
	settings='toolbar=no, location=no, directories=no, status=no, menubar=no, scrollbars='+sb+', resizable=no, copyhistory=yes, width='+w+', height='+h+', screenX='+centerx+' ,screenY='+centery+'';
	win=window.open(url,'_blank',settings);
}